I don't think Nubain use has anything to do with injuries or physical pain. They just want to get high. They may feel it helps the bodybuilding routine somehow but mainly just use narcotics because it feels good.
It is a pain killer first and foremost, so you are wrong. Secondly, while it does have some dysphoric/euphoric effects, there are much better drugs out there if you strictly want to get "high"....
Nubain is still used in some states in Obstetrics patients, although less common as fentanyl and morphine are still good choices.
Either way, you gotta be a fucking moron- Tom Prince, etc to get hooked on the stuff.
-A DUB